error handling with the anydbm module

[cyberparadox]

I am writing a command line dbm editor and have ran into a small issue. If I try to run certain commands (ie add, remove, display) when I do not have a file open, I get the following error:

Traceback (most recent call last):
  File "C:\Users\William\Desktop\dbmEditor.py.py", line 35, in <module>
    for key in file_edit.keys():
  File "C:\Python26\lib\bsddb\__init__.py", line 299, in keys
    self._checkOpen()
  File "C:\Python26\lib\bsddb\__init__.py", line 250, in _checkOpen
    raise error, "BSDDB object has already been closed"
DBError: BSDDB object has already been closed

This is fine and well but I need to do some error handling, but I do not know the syntax. Here is something like I would like it to look like:

if command[0] == 'display':
        try:
            for key in file_edit.keys():
                print repr(key), repr(file_edit[key])
        except DBError:
            print 'No file open'

but this does not work. Following is the whole code:

import anydbm
import tkFileDialog

while True:
    command = raw_input('> ')
    command = command.split(' ')
    if command[0] == 'open':
        file_edit = command[1]
        file_edit = anydbm.open(file_edit, 'c')
    if command[0] == 'opendialog':
       file_edit = tkFileDialog.askopenfilename()
       file_edit = anydbm.open(file_edit, 'c')
    if command[0] == 'close':
        file_edit.close
    if command[0] == 'display':
        try:
            for key in file_edit.keys():
                print repr(key), repr(file_edit[key])
        except DBError:
            print 'No file open'
    if command[0] == 'add':
        file_edit[command[1]] = command[2]
    if command[0] == 'remove':
        ask = raw_input('Remove entry? (y/n)')
        if ask == 'y':
            del file_edit[command[1]]
            print 'Entry Removed'
    if command[0] == 'close':
        file_edit.close()
    if command[0] == 'exit':
        exit()

[jcao219]

from bsddb.db import DBError add that to your code.

[jcao219]

Also you should change the last line to raise SystemExit or anything, unless if you actually have an exit() function.

So here's a better way to write the code:

import anydbm
import tkFileDialog
from bsddb.db import DBError

while True:
    command = raw_input('> ')
    command = command.split(' ')
    try:
        if command[0] == 'open':
            file_edit = command[1]
            file_edit = anydbm.open(file_edit, 'c')
        if command[0] == 'opendialog':
           file_edit = tkFileDialog.askopenfilename()
           file_edit = anydbm.open(file_edit, 'c')
        if command[0] == 'display':
            try:
                for key in file_edit.keys():
                    print key, file_edit[key]  #no need for repr()
            except DBError:
                print 'No file open'
        if command[0] == 'add':
            file_edit[command[1]] = command[2]
        if command[0] == 'remove':
            ask = raw_input('Remove entry? (y/n)')
            if ask == 'y':
                del file_edit[command[1]]
                print 'Entry Removed'
        if command[0] == 'close':
            file_edit.close()
        if command[0] == 'exit':
            raise SystemExit  #or sys.exit()
    except NameError:
        print 'Open a file first!'  #if the user types
                                    #display without
                                    #first opening a file
    except IndexError:
        print 'Invalid command.'    #if the user just
                                    #types "add", "remove",
                                    #or "open" by itself

[cyberparadox]

from bsddb.db import DBError add that to your code.

Thanks, works perfectly. Also your other suggestion works as well

[cyberparadox]

Also you should change the last line to raise SystemExit or anything, unless if you actually have an exit() function.

So here's a better way to write the code:

import anydbm
import tkFileDialog
from bsddb.db import DBError

while True:
    command = raw_input('> ')
    command = command.split(' ')
    try:
        if command[0] == 'open':
            file_edit = command[1]
            file_edit = anydbm.open(file_edit, 'c')
        if command[0] == 'opendialog':
           file_edit = tkFileDialog.askopenfilename()
           file_edit = anydbm.open(file_edit, 'c')
        if command[0] == 'display':
            try:
                for key in file_edit.keys():
                    print key, file_edit[key]  #no need for repr()
            except DBError:
                print 'No file open'
        if command[0] == 'add':
            file_edit[command[1]] = command[2]
        if command[0] == 'remove':
            ask = raw_input('Remove entry? (y/n)')
            if ask == 'y':
                del file_edit[command[1]]
                print 'Entry Removed'
        if command[0] == 'close':
            file_edit.close()
        if command[0] == 'exit':
            raise SystemExit  #or sys.exit()
    except NameError:
        print 'Open a file first!'  #if the user types
                                    #display without
                                    #first opening a file
    except IndexError:
        print 'Invalid command.'    #if the user just
                                    #types "add", "remove",
                                    #or "open" by itself

This works much better. Thanks for all the help!